Target indicating apparatus



June 5, 1956 D. F. REAM 2,749,125

TARGET INDICATING APPARATUS F IG. 2.

I N VENTOR i DONALD F. REAM BY 1M, fl wlih ATTORNEYS Unite Thisinvention relates to a target indicating apparatus and has particularutility in dueling courses of fire for indicating which one of aplurality of targets has been struck first.

In the type of target practice known as dueling, a number of contestantsare involved, there being a separate target for each contestant. Uponreceipt of the signal to tire, each contestant must draw, aim and fireat his specified target as quickly as possible, the winner of thecontest being the one who hits his specified target first. As theproficiency of the contestants increases, the difference between them inthe time taken to draw, aim and fire becomes less and less,,with aconsequent increase in the difficulty of ascertaining which one of thetargets was struck first. Heretofore, it has been the practice toemploy, in some instances, mechanical means for determining whichtarget'was struck first. The inaccuracies of such means stem from thetime lags inherent in any me- 'chanical system and, in addition, in mostmechanical systems, the judgment of the referee in determining whichtarget actuated its mechanical system first. Other indicating systemshave been evolved which involve the use of individual lights or buzzersfor each target, the light being either turned on or off or a buzzersounded when its target is struck. Such a system, while usually fasteracting than the mechanical type, is basically inaccurate because of thetime lag in the filaments of the lamp or the inertia of the buzzerstriker and, usually, the judgment of the referee. In practically alldueling target indicator sys tems, there is the basic problem created bythe targets being located at a considerable distance from thecontes'tants and the referee, with the consequent difliculty oftransmitting the indication from the targets to the referee.

It is an object of this invention to provide a target indicatingapparatus capable of giving an exceedingly accurate indication of when aspecific target has been struck.

It is a further object of this invention to provide a target indicatingapparatus which completely eliminates the element of human judgment indetermining which one of a number of targets was struck first. Anotherobject of this invention is to provide a target indicating apparatus,the indicator portion of which may be located at any reasonable distancefrom the target without impairing the accuracy or operation of thesystem.

Still another object of this invention is to provide a target indicatingapparatus which is simple and efiicient in operation and easy tomaintain in proper working condition.

Still further objects and advantages of this invention will be readilyapparent from the following specification taken in conjunction with thedrawings in which Fig. 1 is a schematic wiring diagram of a targetindicating apparatus embodying the present invention, and

Fig. 2 is aside elevation view of a portion of one of thetargets'showing a projectile passing therethrough.

In accomplishing the aims and objects of this invention, I provide atarget indicating system providing a plurality of targets, usually two,and a control and indicating eleat s Paten locked out like.

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meat capable of being placed at a location remote from the targets. Eachtarget is of the general type shown and described in U. S. Patent474,109 and consists of two electrically conductive plates or screensseparated by dielectric material of a thickness somewhat less than thelength of the bullet or projectile used in target practice. A D. C.voltage is impressed across the plates of the target so that the targetacts as a large condenser.

When a bullet pierces the target, the two plates will be momentariiyshort-circuited and the charge dissipated, thereby creating a very highfrequency discharge pulse. If the indicating element or unit is at adistance remote from the target and connected thereto by any sort ofstandard cable, the. high frequency pulse will be so greatly attenuatedas to be practically useless as a signal. However, after the plates ofthe target are discharged, they will start to charge again as soon asthe short circuit is removed, i. e., the projectile leaves the target.The charging current is of a much longer time base than the dischargepulse, and, consequently, is not attenuated to any great degree by theconnecting cable. By placing the primary of a transformer in seriesbetween one plate of the target and the power supply, I obtain a large,positive voltage pulse in the secondary due to the charging current inthe primary. This positive voltage pulse is fed to the starter electrodeor grid of a cold cathode, gas discharge tube, and is of sufiicientmagnitude to ignite the tube.

In series with the plate circuit of the tube is the coil of a fastacting relay, the normally closed contacts of which are in series withthe plate circuit of a second gas discharge tube, identical to thefirst, which is in the circuit of the second target. Plate current inthe first tube will actuate the fast acting relay, opening the platecircuit of the second tube and preventing it from firing, leaving onlythe first tube ignited, regardless of a subsequent hit on the secondtarget. By providing identical transformers and tube circuits for eachtarget, it will be apparent that whichever target is struck first willignite its corresponding gas tube first, thereby locking out all othertubes. It is obvious that any suitable switch means may be used whichwill act to lock out the other tubes, but by proper proportioning of theelements, and by use of fast acting relays, I have found that myindicating circuit will accurately indicate which target is struck firsteven though a subsequent hit may be made on another target less than onemillisecond later. 'It is obvious that having once the other circuits,any suitable means may be used to "visually indicate which target wasstruck first. In the embodiment here'shown, I-use the cold cathode tubeitself, inasmuch as tubes of this type -glow intensely when ignited,thus affording a clear visual indication to the referee.

Turning now to the drawings, I have shown my invention in an embodimentutilizing two identical targets, 10 and 11, target 1%? having twoelectrodes of electrical conducting material 12 and 14, separated by asuitable dielectric material 16. In a like manner, target 11 haselectrodes 13 and 15, separated by dielectric 17. In order to supply apotential difference to the plates of the targets, any suitable D. C.source may be used. In the embodiment shown I use a standard dry cellbattery 18 of approximately volts, the terminals of which are connectedto a voltage divider network comprising resistors 19, 20, 21 and 22. Aportion of the voltage across the divider is fed through leads 24 and 26to the terminals 28 and 30, to which is connected cable 32, which may beany standard cable, such as a twisted pair or the The wires at the otherend of cable 32 are connected to the target electrodes 12 and 14 asshown, resistor 34'being connected across the electrodes to maintain thepotential difference therebetweem In a like manner, the same .voltage'isfed through leads 23 and 25 to the terminals 27 and 29 which areconnected to cable 31, the wires 'of which are connected to targetelectrodes 13 and as shown. Resistor 33 is connected across theelectrodes to maintain the potential difference therebetween. In serieswith each other in the positive lead 26 between the voltage divider andterminal 3%) are the primary coil 36 of a transformer T2 and a normallyclosed push button switch 38, the purpose of which will be explainedhereinafter. In like manner, in series with positive lead are theprimary coil of transformer T1 and a normally closed push button switch37. The secondary coil of transformer T2 is connected at one end to thegrid or starter electrode 42 of a gas discharge tube V2 and at its otherend through resistance 44 to lead 26 at a point 46 between switch 38 andprimary coil 36. The cathode 48 of tube V2 is connected through loadsand 52 to negative lead 24. Secondary coil 39 of transformer Tlisconnected at one end thereof to the grid or starter electrode 41 of gasdischarge tube V1 and its other end is connected through resistance 43to lead '25 at a point 45 between switch 37 and primary coil .35. Thecathode 47 of tube V1 is connected through leads 49 and 52 to thenegative lead 24. The plate 54 of tube V2 is connected through lead 56to a coil 58 of a relay Rel. 2, resistor 60, contacts 62 of a relay Rel.1 to juncture 64. The juncture 64 is connected through lead 66 to thepositive side of the power supply 18 as best seen in Fig. 1. A switch 68is connected in series between juncture 64 and the positive side of thepower supply. The plate 53 of tube V1 is connected through lead to thecoil 57 of a relay Rel. 1, through a resistor 59, contacts 61 of relayRel. 2 and juncture point 64. It will be apparent that when switch 68and contacts 61 and 62 are closed that both tubes V1 and V2 will have apositive voltage impressed upon their plates. In parallel with coil 58of the relay Rel. 2, there is connected a potentiometer comprisingresistance 70 and arm 72. In like manner, a potentiometer comprisingresistance 69 and arm 71 is connected in parallel with coil 57 of relayRel. 1. Arms 71 and 72 are mechanically coupled together in such amanner that movement of arm 71 to increase the resistance 69 will resultin movement of arm 72 in a direction to decrease the resistance of 70.The reason for this arrangement will be explained hereinafter. Inparallel with resistance is a capacitor 74 and in parallel with resistor59 is a capacitor 73. The function of resistance 60 and capacitor 74 isto increase the speed'of operation of relay Rel. 2 in a mannerprescribed by the manufacturers of such fast acting relays, and it is tobe understood that they form no part of this invention. In like manner,the purpose of resistor 59 andcapacitor 73 is to increase the speed ofoperation of relay Rel. 1.

Having described the circuitry of my device, I will now explain theoperation thereof. When battery 18 is connected into the circuit, thevoltage output of the battery will be divided by voltage divider network19, 20, 21 and 22, and a portion of that voltage will be impressedacross the target electrodes 12 and 14 and 13 and 15. When switch 68 isclosed, a positive voltage will be impressed on the plates of tubes V1and V2 the contacts of relays Rel. 1 and Rel. 2 being normally closed.Assuming now that a bullet'strikes target 10 before a bullet strikestarget 11, at the instant the bullet reaches the position shown in Fig.2 the electrodes 12 and 14 will be shorted together and :the potentialdifference between them will .be dissipated. It will be apparent that ifthe spacing between the plates 12 and 14 is approximately; inch and abullet 95. inch in length and traveling at approximately 2,000 feet persecond strikes the target, thelength of time that the plates 12 and 14are connected togetherrbythe bullet will be on theorder of 10microseconds. vThis timeinterval is sufficient for the charge ontheplates12 and 14 to be largely dissipated. This .dischargeiresults ina high frequency pulsehaving a time base of approximately 10microseconds, which will be -rapidly attenuated in the cable 32. Afterthe projectile has ceased to short electrodes 12 and 14 to gether, thepower supply will act to charge the plates again through the voltagedivider network, resulting in a momentary surge of charging current of amuch longer time base than the discharge pulse. This charging current,in passing through coil 36 of transformer T2 will act to impress throughsecondary 40 a positive voltage on grid 42 of sufiicient magnitude andduration to fire tubc V2. The plate current of tube V2 will then flowfrom the positive side of power supply 18, through switch 68, lead 66,junction 64, contacts 62, resistor 60, coil 58, and lead 56, through thetube, lead 50, and lead 52 to the negative side of the power supply.Coil 58 of relay Rel. 2 will be energized by this plate current andcontacts 61 will be opened. Inasmuch as the plate circuit of tube V1includes contacts 61, when these contacts are open, the positive voltageimpressed upon the plate 53 of tube V1 will be removed, and V1 will beinoperative. Inasmuch as the response time of relays Rel. 1 and Rel. 2is of the order of V of a millisecond, it will be readily apparent thata bullet striking target 11 approximately 55 of a millisecond after abullet struck target Etl will not act to fire tube V1. Any suitablemeans might be used to indicate that tube V2 has been ignited due totarget 10 being struck first. In practice, I have found that the glow ofthe tubes V1 and V2 is sutficiently strong to be readily perceptible tothe naked eye and thus the tube itself may act as the indicator. Afterthe referee has recorded the results, he opens switch 68, removing thepositive voltage from the plates of both tubes V1 and V2, andextinguishes the tube that is firing When switch 68 is closed, thecircuit is in condition to indicate the next dueling course. If target11 had been struck first instead of target 10, the operation would havebeen identical except that tube V1 would have been ignited and relayRel. 1 activated, opening contacts 62 and locking out tube V2. In theevent that both targets are struck in less than approximately 1 of amillisecond, both tubes V1 and V2 will be ignited momentarily and beextinguished as both re lays Rel. 1 and Re]. 2 will be activated,opening the plate circuits of both tubes. Thus, if the referee sees bothtubes ignite and then go out, he will record the results as a tie. Inorder that there will be no interchange of energy between targets 10 and11 when one of the targets is struck, I provide a capacitor 76 connectedacross the output of the voltage divider to the targets, to maintain astable D. C. potential across the target electrodes 12, 14 and 13, 15.Due to the use of capacitor 76, the voltage distribution across thevoltage divider network 19, 20, 21, 22 remains substantially constant atall times. even during the recharging period following the discharge ofthe target plates by a projectile. Upon the discharge of either targetby passage of a projectile, capacitor 76 provides substantially all ofthe recharging current for the discharged target, capacitor 76 itselfbeing recharged through the voltage divider network following theactuation of indicating tube V1 or V2. The time required to rechargecapacitor 76 is substantially a function of the R-C time constant ofcapacitor 76 and the parallel connected arms 20 and 22 of the voltagedivider under normal operating conditions, assuming switch 78 to beclosed. Any redistribution of voltages across the voltage dividernetwork in connection with the recharging of capacitor 76 isnegligibleand is not sutficient to produce any significant effect on thetargets or on their associated indicator circuits. In addition,capacitor 76 reduces the A. C. impedance of the voltage divider so thatthe charging'cm'rent will be a maximum.

It is apparent that a difference in the speed of action. between thecombinations Tl, V1 and Rel. 1 and T2, V2'and Re]. 2 will weigh theresults of near-simultaneous target hits in favor of one target andagainst the other.

In order that these action times may be balanced, I have provided thepotentiometers 70, 72 and 69, 71 in shunt with the relay coils 58 and57, respectively. Since the action time of the relays is approximatelyproportional to the current through their coils, movement of arm 72 in agiven direction will increase the time of action of the circuitcombination of T2, V2 and Rel. 2 and at the same time decrease, throughthe mechanical connection to arm 71, the action time of the circuit ofT1, V1 and Rel. 1. By connecting the two sets of target terminals inparallel and shorting one set such as 28, 30, a simultaneous hit on eachtarget is simulated and the potentiometers may be adjusted until suchsimultaneous hit results in a momentary flashing and then extinguishingof both tubes J1 and V2.

When the circuit, targets and cables are connected, there is need for anindicator to show that the leads to the targets and the targetsthemselves are not inadvertently shorted and also to show that thetarget leads are continuous and not open. Also, there is need within thecircuit for a voltage meter which shows the condition of the battery.All of these conditions can be shown on a meter M1 of the milliammetertype when connected in one arm of the voltage divider network as shownin Fig. 1. A switch 78 is connected into the voltage divider networkbetween the junction points of resistors 19, 20 and resistors 21, 22 fora purpose which will be explained hereinafter. When the leads to thetargets are continuous and neither the leads nor the targets areshorted, there is a complete circuit from the battery to the targets,through resistors 33 and 34, and back to the battery, and the meter isadjusted to indicate approximately 0.5 full scale. Thereafter, if theleads to either or both targets be open, the meter will read well above0.5 full scale. If either of the targets or the leads be shorted, themeter will read well below 0.5 full scale. Opening switch 78 will havethe effect of converting the milliammeter M1 into a voltage meter whichwill register approximately 0.5 full scale when the battery voltage isin the neighborhood of its rated voltage output. The switches 37 and 38permit the operator to'determine in which of the two target circuits anopen or short has occurred. Thus, if the leads to target for instanceare open, the meter will read greater than 0.5 full scale and openingswitch 38 will have no efiect upon the meter reading. On the other hand,suppose that the leads to target it), for instance, are shorted, inwhich case the meter will read less than 0.5 full scale. Opening ofswitch 38 will then cause deflection of the meter to greater than 0.5full scale. 1

I have found in practice that a battery of approximately 90 volts outputand a voltage divider network so pro' portioned as to give a potentialdifference of approximately 21 volts across the target electrodes givesexcellent results. However, it will be obvious that other values mayserve equally as well without impairing the operation of the targetindicator system.

From the foregoing, it can be seen that if cables 31 and 32 are simplythe standard twisted pair wound on drums, as is both convenient andcustomary, the attenuation of high frequencycurrents will be exceedinglylarge. Furthermore, this attenuation will be increased as the lengths ofthe cable are increased. By use of low frequency currents as explainedheretofore, my indicator has functioned perfectly using twisted paircables up to a distance of A of a mile, and shorter distances Whereinthe excess length of cable was wound on the drums. ,It is readilyapparent that a great saving in expense is made with my system in theuse of standard cable alone instead of expensive high frequency-cable,not to mention the convenience and efficiency to be gained by usingdrums or reels to carry the excess cable.

While I have shown and described my invention as used in a duelingcourse of fire system, it having particular utility in such anarrangement, it is obvious that an indicating system for signaling hitson a single target may be had byutilizing only one target and theindicator circuit components associated therewith.

What I claim is:

1. In a target shooting apparatus, a plurality of targets, each of saidtargets comprising a plurality of electrically conductive plates spacedapart and insulated from each other; means for connecting each of saidtargets to a power supply source for charging the plates of each of saidtargets to establish a potential dilference therebetween, said platesbeing adapted to be discharged by passage of a projectile through thetarget; and an indicator circuit associated with each of said targetsand responsive to the charging current of its associated target forindicating when said associated target has been struck first, and meanslinking the indicator circuit of each target with the indicator circuitsof the other targets for signaling to the circuits of the other targetswhen the respective target has been struck first.

2. In a target shooting apparatus, a plurality of targets, each of saidtargets comprising a plurality of electrically conductive plates spacedapart and insulated from each other; means for connecting each of saidtargets to a power supply source for charging the plates of each of saidtargets to establish a potential difierence therebetween, said platesbeing adapted to be discharged by passage of a projectile through thetarget; and an indicator circuit associated with each of said targetsand responsive to the charging current of its associated target forindicating when said associated target has been struck first, and meansresponsive to the charging current of the target which has been struckfirst to lock out the indicator circuits associated with the targetswhich have not been struck first.

3. In a target shooting apparatus, a plurality of targets, each of saidtargets comprising a plurality of electrically conductive plates spacedapart and insulated from each other; means for connecting each of saidtargets to a power supply source for charging the plates of each of saidtargets to establish a potential diflference therebetween, said platesbeing adapted to be discharged by passage of a projectile through thetarget; and an indicator circuit associated with each of said targetsand responsive to the charging current of its associated target forindicating when said associated target has been struck first, and meansalso responsive to the charging current of the target which has beenstruck first for locking out the indicator circuits associated with thetargets which have not been struck first. I 4. In a target shootingapparatus, a plurality of target each of said targets comprising aplurality of electrically conductive plates spaced apart and insulatedfrom each other; means for connecting each of said targets toa powersupply source for charging the plates of each of said targets toestablish a potential difierence therebetween, said plates being adaptedto be discharged by passage of a projectile through the target; and anindicator circuit associated with each of said targets and responsive tothe charging current of its associated target for indicating when saidassociated target has been struck first, and switch means responsive tothe charging current of the target which has been struck first forlocking out the indicator circuits associated with the targets whichhave not been struck first.

5. In a target shooting apparatus, a plurality of targets, each of saidtargets comprising a plurality of electrically conductive plates spacedapart and insulated from each other; means for connecting each of saidtargets to a power supply source for charging the plates of each of saidtargets to establish a potential difference therebetween, said platesbeing adapted to be discharged by passage of a projectile through thetarget, and an indi cator circuit associated with each of said targetsand responsive to the charging current of its associated target forindicating when said associated target has been struck 7 first, eachofsaid circuits including a relay having normally closed contacts whichareserially connected in each of the other circuits with said power supplysource whereby actuation of the relay in one circuit will open saidcontacts to prevent the other circuits from responding to the chargingcurrent of their associated targets.

6. In a target shooting apparatus, a plurality of targets, each of saidtargets comprising a plurality of electrically conductive plates spacedapart and insulated from each other; means for connecting each of saidtargets to a power supply source for charging the plate of each of saidtargets to establish a potential difference therebctween, said platesbeing adapted to be discharged by passageci a projectile through thetarget, and an indicator circuit associated with each of said targetsand responsive to the charging current of its associated target forindicating when said associated target has been struck first, each ofsaid circuits including a relay having normally closed contacts whichare serially connected in each of the other circuits with said powersupply source whereby actuation of the relay in one circuit will opensaid contacts to prevent the other circuits from responding to thecharging current of their associated targets; and switch means connectedin series between the power supply source and each of the other circuitsfor decnergizing all of the circuits simultaneously for manuallyresetting the indicator circuits.

7. In a target shooting apparatus, a plurality of targets, each of saidtargets comprising a plurality of electrically conductive plates spacedapart and insulated from each other; means for connecting each of saidtargets to a power supply source of D. C. voltage, a voltage dividernetwork, a condenser, and a resistor in parallel with the plates of eachof said targets for charging the plates of each of said targets toestablish a potential difference therebetween, said plates being adaptedto be discharged by passage of a projectile through the target; anindicator circuit associated with each of said targets and responsive tothe charging current of its associated target for indicating when saidassociated target has been struck first, and means linking the indicatorcircuit of each target with the indicator circuits of the other targetsfor signaling to the circuits of the other targets when the respectivetarget has been struck first.

8. In a target shooting apparatus, a plurality of targets, each of saidtargets comprising a plurality of electrically conductive plates spacedapart and insulated from each other; means for connecting each of saidtargets to a power supply source of D. C. voltage, a voltage dividernetwork. a condenser, and a resistor in parallel with the plates of eachof said targets for charging the plates of each of said t sts toestablish a potential difference therebetwcen, s to; being adapted to bedischarged by passage of a p cctile through the target; an indicatorcircuit associated with each of said targets and responsive to thecharging current of its associated target for indicating when saidassociated target has been struck first, each of said indicator circuitsincluding a transformer having its primary winding in series between thevoltage divider and its associated target, a cold cathode gas-filledtube having a cathode, anode, and control electrode, the secondary ofsaid transformer being in series with said control electrode. and meanslinking the indicator circuit of each tar-get with the indicatorcircuits of the other targets for signaling to the circuits of the othertargets when the respective target has been struck first.

9. in a target shooting apparatus, a plurality of targets, each of saidtargets comprising a plurality of electrically conductive plates spacedapart and insulated'from each other: means for connecting each of saidtargets to a power supply source of D. C. voltage, a voltage'dividernetwork, a condenser, and a resistor in parallel with the plates of eachof said targets for charging the plates of each of said targets toestablish a potential difference therebetween, said plates being adaptedto be discharged tit by passage 'of a projectile through the target; andan indicator circuit associated with each of said targets and responsiveto the charging current of its associated target for indicating whensaid associated target has been struck first, each of said indicatorcircuits including a transformer having its primary winding in seriesbetween the voltage divider and its associated target, a cold cathodegas-filled tube having a cathode, anode, and control electrode, thesecondary of said transformer being in series with said controlelectrode, and a relay coil in series with the anode of said gas-filledtube, the contacts associated with said relay coil being normally closedand connected in series with the anode of each of the gas-filled tubesin the indicator circuits associated with the other targets.

10. In a target shooting apparatus, a plurality of targets, each of saidtargets comprising a plurality of electrically conductive plates spacedapart and insulated from each other; means for connecting each of saidtargets to a power supply source of D. C. voltage, a voltage dividernetwork, a condenser, and a resistor in parallel with the plates of eachof said targets for charging the plates of each of said targets toestablish a potential difference therebetween, said plates being adaptedto be discharged by passage of a projectile through the target; and anindicator circuit associated with each of said targets and responsive tothe charging current of its associated target for indicating when saidassociated target has been struck first, each of said indicator circuitsincluding a transformer having its primary winding in series between thevoltage divider and its associated target, a cold cathode gas-filledtube having a cathode, anode and control electrode, the secondary ofsaid transformer being in series with'said control electrode, and arelay coil in series with the anode of said gas-filled tube, thecontacts associated with said relay coil being normally closed andconnected in series with the anode of each of the gas-filled tubes inthe indicator circuits associated with the other targets, and meansassociated with each relay coil for regulating the flow of currenttherethrough.

11. In a target shooting apparatus, a plurality of targets, each of saidtargets comprising a plurality of electrically conductive plates spacedapart and insulated from each other; means for connecting each of saidtargets to a power supply source of D. C. voltage, a voltage dividernetwork, a condenser, and a resistor in parallel with the plates of eachof said targets for charging the plates of each of said targets toestablish a potential difference therebetween, said plates being adaptedto be discharged by passage of a projectile through the target; and anindicator circuit associated with each of said targets and responsive tothe charging current of its associated target for indicating when saidassociated target has been struck first, each of said indicator circuitsincluding a transformer having its primary winding in series betwecn'thevoltage divider and its associated target, a cold cathode gas-filledtube having a cathode, anode and control electrode, the secondary ofsaid transformer bein series with said control electrode, and a relaycoil in series with the anode of said gas-filled tube, the contactsassociated with said relay coil being normally closed and connected inseries with the anode of each of the gasiilled tubes in the indicatorcircuits associated with the other targets, and means associated witheach relay coil for regulating the flow of current therethrough, saidmeans comprising a potentiometer in parallel with said relay coil, theadjusting arms of each of the said potentioineters being mechanicallycoupled together for simultaneous adjustment.

12. in a target shooting apparatus, a plurality of targets, each of saidtargets comprising aplurality of electrically conductive plates spacedapart and insulated from each other; means for connecting each of saidtargets to a power supply source of D. C. voltage, a voltage dividernetwork, a condenser, and a resistor in parallel with the plates of eachof said targets for charging the plates of each of said targets toestablish a potential difierence therebetween, said plates being adaptedto be discharged by passage of a projectile through the target; and anindicator circuit associated with each of said targets and responsive tothe charging current of its associated target for indicating when saidassociated target has been struck first, each of said indicator circuitsincluding a transformer having its primary winding in series between thevoltage divider and its associated target, a gas-filled tube having acathode, anode, and control electrode, the secondary of said transformerbeing in series with said control electrode, and a relay coil in serieswith the anode of said gas-filled tube, the contacts associated withsaid relay coil being normally closed and connected in series with theanode of each of the gas-filled tubes in the indicator circuitsassociated with the other targets; and means for testing each of saidindicator circuits including a milliammeter in series with one arm ofthe voltage divider, a switch between the mid-point of the arms of thevoltage divider, and a switch in series with the primary winding of eachof the transformers, whereby open and short circuit conditions andproper operating conditions may be ascertained.

13. In a target shooting apparatus, a target comprising a plurality ofelectrically conductive plates spaced apart and insulated from eachother, said plates being adapted to be discharged by passage of aprojectile through the target, charging circuits means for connectingsaid plates of said target to a power supply of D. C. voltage, saidcharging circuit means having a sufficiently high impedance to cause thetime base of the charging of said plates to be substantially longer thanthe time base of the discharge of said plates, and an indicating meansassociated with said charging circuit means in such manner as to beresponsive to the charging current.

14. A target shooting apparatus as defined in claim 13, in which themeans associating the indicating means with said charging circuit meansincludes means inductively coupling said charging circuit means to saidindicating means.

15. A target shooting apparatus as defined in claim 13, in which saidindicating means comprises an electronic device responsive to thecharging current.

References Cited in the file of this patent UNITED STATES PATENTS474,109 Vogel May 3, 1892 2,185,628 Daum Jan. 2, 1940 2,241,135 Jaimetet al. May 6, 1941 2,576,960 McAvoy Dec. 4, 1951

